The purpose of this Law is to show the truth behind a doctrine in a “proving manner”.
Here is the verse from which this explanation of the â€œLaw of Two Witnessesâ€ is based.
This is the third time I am coming to you. In the mouth of two or three witnesses shall every word be established.
2 Corinthians 13:1
There must be at least two verses to affirm a doctrine (a teaching). Two which affirm the above verse would be Deuteronomy 17:6 or 19:15.
At the mouth of two witnesses, or three witnesses, shall he that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death.
One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.
The purpose is to show the two witnesses are necessary to prove something to be true or false. In this case a teaching from the Bible.